In engineering practice, the most widely used regulator control law proportional, integral, differential control, referred to as PID control, also known as PID regulation. PID controllers come out has been nearly 70 years of history, with its simple structure, good stability, reliable, easy to adjust and become one of the major technology industry control. When the controlled object structure and parameters can not fully grasp, or can not get an accurate mathematical model, the time control theory is difficult to use other techniques, structure and parameters of the system controller must rely on experience and on-site commissioning to determine at this application PID control technology most convenient. When that is, when we do not fully understand a system and controlled object, or can not be a valid measurement tools to get the system parameters, the most suitable PID control technology. PID control, in practice there are PI and PD control. PID controller is based on the error of the system, using proportional, integral and differential control to calculate the amount of control.